Such a suspension thrust bearing device usually comprises a rolling bearing forming an axial thrust and comprising an upper ring and a lower ring between which a plurality of rolling elements are placed, for example balls or rollers. Preferably, a rolling bearing with oblique contact is used making it possible to absorb both the radial forces and the axial forces exerted on the device. The upper and lower rings are usually mounted in contact with upper and lower bearing or support parts such as dishes or caps. The upper and lower caps form a housing for the rings of the rolling bearing and make it possible to provide the interface between the said rings and the adjacent elements.
Such a suspension thrust bearing device is placed in the upper portion of a MacPherson strut between the body of the vehicle and a suspension spring. The spring is usually installed around a damper piston rod the end of which is connected to the body of the vehicle by means of an elastic block filtering the vibrations. The suspension spring, usually a helical spring, rests axially directly or indirectly on the lower bearing cap of the suspension thrust bearing device. For its part, the upper bearing cap is fixed relative to the body of the vehicle.
Such a suspension thrust bearing device makes it possible to transmit axial forces between the suspension spring and the body of the vehicle while allowing a rotary movement between the lower bearing cap and the filtering elastic block resulting from a turning of the steered wheels of the vehicle and/or from the compression of the suspension spring.
Patent applications FR-A1-2 811 264, FR-A1-2 857 906 and WO-A1-2009/030842 describe such suspension thrust bearing devices comprising a lower supporting cap and a rolling bearing mounted so as to rest against it. The lower supporting cap is made of synthetic material and comprises a metal reinforcing framework or insert improving the mechanical strength of the cap against the forces exerted by the suspension spring.
Since the reinforcing insert is made of metal, it is necessary to sink it fully inside the lower supporting cap in order to avoid having recourse to anti-corrosion surface treatments such as electrophoresis. Specifically, these treatments are quite costly and using them causes pollution.
Moreover, the method for manufacturing such a cap is relatively protracted and complex because the reinforcing insert has to be formed first by cutting and swaging a metal sheet blank and then the synthetic material of the cap has to be overmoulded onto the insert thus formed. Moreover, the insert increases the overall weight of the lower supporting cap and more generally that of the suspension thrust bearing device.
The object of the present invention is to remedy these drawbacks.